I have a 2000 Bravada that is fairly new to me. The problem that I need the most help with is the smart track is engaged at all times.

I have pulled the "4WD" fuse and test driven and can then instantly feel that the truck is now in 2WD as it should be. I do not have any MIL showing any problems but have not had it scanned for any codes.

1) Tires are well worn but are all evenly worn across the set.
2) tire pressure is correct.
3) I have done the blue autotrac transfer case fluid change already since the PO acknowledged the car did bind when making very tight parking lot turns. He was given a bit of the run around trying to get it fixed.."they all do this" etc..

I have no previous GM experience but I worked for a toyota dealer for 6 years (ASE mastertech) in my previous career. This is my first personal car new enough to be an OBD2 car so until now I have not had any reason to own a scan tool. Will the affordable scan tools allow you to see any codes that pertain to the drive line? I assume that if the encoders/speed sensors were totally bad there would be a MIL of some kind?

How sensitive are these vehicles to tire wear? I don't want to put on new tires until this problem is fixed - but it would be ironic if worn tires was the cause of these problems?
Is there a spec for allowable tire diameter variation?

looking for some insight from experienced techs who have fixed the smart track systems. 1) Is the TCCM looking at encoders in the transfer case?
2) If so are there 2 - one for each drive shaft?
3) Since it seems that the transfer case motor engages and disengages with the fuse pulled. Is it safe to say the problem is elsewhere?
4) since there are no "service AWD" or CEL is is safe to assume that the TCCM "BELIEVES" that the encoderes are working properly?

I have a 2000 Bravada that is fairly new to me. The problem that I need the most help with is the smart track is engaged at all times.

I have pulled the "4WD" fuse and test driven and can then instantly feel that the truck is now in 2WD as it should be. I do not have any MIL showing any problems but have not had it scanned for any codes.

1) Tires are well worn but are all evenly worn across the set. 2) tire pressure is correct.3) I have done the blue autotrac transfer case fluid change already since the PO acknowledged the car did bind when making very tight parking lot turns. He was given a bit of the run around trying to get it fixed.."they all do this" etc..

I have no previous GM experience but I worked for a toyota dealer for 6 years (ASE mastertech) in my previous career. This is my first personal car new enough to be an OBD2 car so until now I have not had any reason to own a scan tool. Will the affordable scan tools allow you to see any codes that pertain to the drive line? I assume that if the encoders/speed sensors were totally bad there would be a MIL of some kind?

How sensitive are these vehicles to tire wear? I don't want to put on new tires until this problem is fixed - but it would be ironic if worn tires was the cause of these problems? Is there a spec for allowable tire diameter variation?

looking for some insight from experienced techs who have fixed the smart track systems. 1) Is the TCCM looking at encoders in the transfer case? 2) If so are there 2 - one for each drive shaft?3) Since it seems that the transfer case motor engages and disengages with the fuse pulled. Is it safe to say the problem is elsewhere?4) since there are no "service AWD" or CEL is is safe to assume that the TCCM "BELIEVES" that the encoderes are working properly?

Where should I look next?

Matt

you need to get it scanned ,get me a code and I'll look it up for you.

2) Any comment on the scan tools - I have been waiting for an excuse to get one for personal use, this looks like it. Will the consumer tools give access to all codes that are stored?

Or when you say "get it scanned" do you mean take it to a shop with a tech2 for any or all TCCM drive line have messages?

I answered this already today but it didn't go thru,so jobber scanners should read all codes,I have never used 1,only the tech 2,they are awsome and very expensive @$3000.,I do expect to see a code,may be someone else can chime in here about jobber scanners

our service info locked me out here at home for some reason(si changed 2 days ago,not sure if related)so I can't look up your truck,I will post the diag table for 4wd not disengaging tomorrow AM,9AM eastern,7 am my time,well 7:20 actually later

The NV136 transfer case is an automatic transfer case with two drive ranges. Shifting from rear wheel drive to four wheel drive is done automatically when the transfer case shift control module receives wheel rotating slip information from the speed sensors. The transfer case shift control module then engages the transfer case motor/encoder to position the transfer case from rear to four wheel drive. When the transfer case shift control module receives information that the wheel rotation is the same on both axles, the transfer case shift control module sends position information to the motor/encoder to put the transfer case back into rear wheel drive. The 2HI position is for normal driving with the rear wheels pushing the vehicle. The 4 wheel drive position is for driving through sand, snow, mud, gravel, or heavy rain at normal or slightly below normal speeds. The NV136 is manufactured at Syracuse New York by New Venture Gear a division of New Process Gear for General Motors.